Ultrasonic sensing wear life of ground engaging tools

ABSTRACT

A wear life sensing system may use nondestructive testing techniques to determine when ground engaging tools (GETs) are worn down and reach the ends of their useful wear lives. The wear life sensing system may include a wear sensing body and a wear sensor assembly embedded within the body of the GET. The wear sensing body is positioned proximate a maximum wear point of the GET and is fabricated from a material having a different material density than the material of the GET body. The wear sensor assembly outputs distance sensor signals in the direction of the wear sensing body and determines the presence or absence of the wear sensing body based on the reflected distance sensor signals received at the wear sensor assembly. The wear sensor assembly may transmit a GET replacement message when it no longer detects the presence of the wear sensing body.

TECHNICAL FIELD

The present disclosure relates generally to earth working machines withground engaging implements and, in particular, to wear detection in wearsurfaces and ground engaging tools (GETs) of such ground engagingimplements to determine when the wear surfaces and GETs reach the endsof their useful wear lives.

BACKGROUND

Earth moving machines known in the art are used for digging into theearth or rock and moving loosened work material from one place toanother at a worksite. The machines and equipment include articulatingmechanical arms or other types of linkages for manipulating one or moreimplements of the machine. The linkages are capable of raising, loweringand rotating the implements to engage the ground or other work materialin a desired manner. In the earth moving applications, the implements ofthe machines or other equipment may be buckets provided with a beveledlip or blade on a base edge for moving or excavating dirt or other typesof work material. In other applications, implements can include rippers,blades, thumbs and the like that dig into the work material.

To facilitate the earth moving process, and to prolong the useful lifeof buckets and similar implements, a plurality of tooth assemblies maybe spaced along the material engaging edge of the implement and attachedto the surface of the implement. The tooth assemblies project forwardfrom the material engaging edge as a first point of contact andpenetration with work material, and to reduce the amount of wear of thematerial engaging edge. With this arrangement, the tooth assemblies aresubjected to the wear and breakage caused by repetitive engagement withthe work material. Eventually, the tooth assemblies must be replaced,but the implement remains usable through multiple cycles of replacementtooth assemblies. Other types of GETs may be attached to buckets orother implements at points where the most wear is expected to occur,such as edge protectors, corner guards, cutting edges and the like.

In many implementations, installation and replacement of the toothassemblies may be facilitated by providing the tooth assemblies as atwo-part system. The system may include an adapter that is attached tothe material engaging edge of the implement, a ground-engaging tipconfigured to be attached to the adapter, and a retention mechanismsecuring the tip to the adapter during use. The adapter may be welded,bolted or otherwise secured to the base edge, and then the tip may beattached to the adapter and held in place by the retention mechanism.The tip endures the majority of the impact and abrasion caused byengagement with the work material, and wears down more quickly andbreaks more frequently than the adapter. The point at a tip is worn downto the point that its useful life is exhausted and the tip should bereplaced may be known in the abstract, but it may be difficult todetermine in the field that the tip has reached that point.

One example of a strategy for monitoring the wear on a ground engagingtip is illustrated and described in U.S. Pat. Appl. Publ. No.2015/0149049 A1 to Bewley et al. The Bewley et al. publication disclosesa process and tool for monitoring the status, health, and performance ofwear parts used on earth working equipment. In one embodiment, amonitoring system has one or more electronic sensors to determine acurrent length of a wear member on an edge of a bucket. The monitoringsystem is installed on a bridge or top of the bucket, and electronicsensors have a clear line of site to the wear members during use.Features may be incorporated onto the wear member to aid in determiningthe degree the wear member has been worn. The wear member may containmultiple features along the length of the expected wear profile so thatas the wear member wears, the monitoring system is able to detect thenumber of features remaining on the wear member.

SUMMARY OF THE DISCLOSURE

In one aspect of the present disclosure, a ground engaging tip of aground engaging tooth assembly for an implement of a work machine thatengages a work material with a base edge of the implement to dig intothe work material is disclosed. The ground engaging tip may include atip body having an exterior surface shaped to penetrate the workmaterial into which the base edge of the implements digs, an adaptercavity surface defining an adapter cavity for receiving an adapter noseof an adapter of the ground engaging tooth assembly to mount the groundengaging tip on the adapter, and a first wear sensor cavity surfacedefining a first wear sensor cavity within the ground engaging tip,wherein the tip body is fabricated from a GET body material having a GETbody material density. The ground engaging tip may further include afirst wear sensing body embedded in the tip body at a first locationindicative of a first maximum GET wear point of the ground engaging tip,wherein the first wear sensing body is fabricated from a wear sensingbody material having a wear sensing body material density that is notequal to the GET body material density, and a first wear sensor assemblydisposed within the first wear sensor cavity. The first wear sensorassembly may include a first distance sensor for transmitting outputdistance sensor signals and for receiving reflected distance sensorsignals that are reflected from an object or a surface of the tip body,and a first sensor assembly controller operatively connected to thefirst distance sensor. The first sensor assembly controller may beconfigured to cause the first distance sensor to transmit the outputdistance sensor signals, to detect receipt of the reflected distancesensor signals at the first distance sensor, to determine whether thefirst wear sensing body is still embedded in the tip body proximate thefirst maximum GET wear point based on a value of the reflected distancesensor signals, and to cause a GET replacement message to be transmittedfrom the first wear sensor assembly in response to determining that thefirst wear sensing body is no longer embedded in the tip body.

In another aspect of the present disclosure, a method for sensing anamount of wear in a ground engaging tool for an implement of a workmachine that engages a work material to dig into the work material isdisclosed. The method may include transmitting output distance sensorsignals through a GET body of the ground engaging tool from a firstdistance sensor of a first wear sensor assembly disposed within a firstwear sensor cavity within the GET body, wherein the GET body isfabricated from a GET body material having a GET body material density,and wherein a first wear sensing body is embedded in the GET body at afirst location indicative of a first maximum GET wear point of theground engaging tool, and the first wear sensing body is fabricated froma wear sensing body material having a wear sensing body material densitythat is not equal to the GET body material density. The method mayfurther include receiving reflected distance sensor signals at the firstdistance sensor that are reflected from one of an object or a surface ofthe GET body, determining at the first wear sensor assembly whether thefirst wear sensing body is still embedded in the GET body proximate thefirst maximum GET wear point based on a value of the reflected distancesensor signals, and transmitting a GET replacement message from thefirst wear sensor assembly in response to determining that the firstwear sensing body is no longer embedded in the GET body.

In a further aspect of the present disclosure, a ground engaging toolfor an implement of a work machine that engages a work material to diginto the work material is disclosed. The ground engaging tool mayinclude a GET body having an exterior surface shaped to penetrate thework material into which the implements digs, and a first wear sensorcavity surface defining a first wear sensor cavity within the GET body,wherein the GET body is fabricated from a GET body material having a GETbody material density. The ground engaging tool may further include afirst wear sensing body embedded in the GET body at a first locationindicative of a first maximum GET wear point of the ground engagingtool, wherein the first wear sensing body is fabricated from a wearsensing body material having a wear sensing body material density thatis not equal to the GET body material density, and a first wear sensorassembly disposed within the first wear sensor cavity. The first wearsensor assembly may include a first distance sensor for transmittingoutput distance sensor signals and for receiving reflected distancesensor signals that are reflected from an object or a surface of the GETbody, and a first sensor assembly controller operatively connected tothe first distance sensor. The first sensor assembly controller may beconfigured to cause the first distance sensor to transmit the outputdistance sensor signals, to detect receipt of the reflected distancesensor signals at the first distance sensor, to determine whether thefirst wear sensing body is still embedded in the GET body proximate thefirst maximum GET wear point based on a value of the reflected distancesensor signals, and to cause a GET replacement message to be transmittedfrom the first wear sensor assembly in response to determining that thefirst wear sensing body is no longer embedded in the GET body.

Additional aspects are defined by the claims of this patent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a loader bucket having GETs attachedthereto;

FIG. 2 is an isometric view of an excavator bucket having GETs attachedthereto;

FIG. 3 is an isometric view of an exemplary GET in the form of a toothassembly that may incorporate a wear life sensing system in accordancewith the present disclosure;

FIG. 4 is a side view of the tooth assembly of FIG. 3;

FIG. 5 is a cross-sectional view of a ground engaging tip including awear sensor assembly and wear sensing body in accordance with thepresent disclosure;

FIG. 6 is a schematic illustration of electrical and control componentsof the wear sensor assembly of the wear life sensing system of FIG. 5and of an external GET wear test device

FIG. 7 is a block diagram of a GET wear life testing routine inaccordance with the present disclosure that may be executed by the wearlife sensing system of FIGS. 5 and 6;

FIG. 8 is the cross-sectional view of the ground engaging tip of FIG. 5worn down but not at the end of its useful wear life;

FIG. 9 is the cross-sectional view of the ground engaging tip of FIG. 5worn down to a maximum GET wear point;

FIG. 10 is the cross-sectional view of the ground engaging tip of FIG. 5with an alternative embodiment of the wear life sensing system having asecond wear sensor assembly and a second wear sensing body proximate asecond maximum GET wear point;

FIG. 11 is the cross-sectional view of the ground engaging tip of FIG. 5with a further alternative embodiment of the wear life sensing systemhaving a second wear sensing body proximate a partial GET wear point;and

FIG. 12 is a block diagram of a modified GET wear life testing routinein accordance with the present disclosure that may be executed by thewear life sensing assembly of FIGS. 5 and 6 with the alternativeembodiment of the wear life sensing system of FIG. 11.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is shown an implement for abottom-wearing application, such as a loader machine, in the form of aloader bucket assembly 1. The loader bucket assembly 1 includes a loaderbucket 2 which is partially shown in FIG. 1. The loader bucket 2 is usedon the loader machine to excavate work material in a known manner. Thebucket assembly 1 may include several GETs including a pair ofoppositely-disposed support arms 3 on which corresponding corner guards4 may be mounted. The bucket assembly 1 may further included a number ofedge protector assemblies 5 interposed between tooth assemblies 10, withthe edge protector assemblies 5 and the tooth assemblies 10 beingsecured along a base edge 18 of the loader bucket 2. FIG. 2 illustratesan implement for a top-wearing application, such as an excavator, in theform of an excavator bucket assembly 6. The excavator bucket assembly 6includes an excavator bucket 7 having corner guards 4 connected oneither side, and a plurality of tooth assemblies 10 attached across thebase edge 18 of the excavator bucket 7. Various embodiments of toothassemblies 10 may be described herein that may be implemented inbottom-wearing and top-wearing applications. However, those skilled inthe art will understand that wear life sensing systems an accordancewith the present disclosure may be implemented in many differentconfigurations of tooth assemblies 10 and in implements used in diversebottom-wearing and top-wearing implementations. Moreover, the wear lifesensing systems may be implemented in a similar manner in other GETs forimplements that experience wear such as the corner guards 4, the edgeprotector assemblies 5, and the base edge 18, as well as GETs on othertypes of implements. The illustration and description of the wear lifesensing system in the tooth assemblies 10 is exemplary, and thoseskilled in the art will understand how to implement the wear lifesensing system in other GETs based on the disclosure provided herein.

FIGS. 3 and 4 illustrate an embodiment of an exemplary tooth assembly 10that may be useful with earth moving implements, and in which a wearlife sensing system in accordance with the present disclosure may beimplemented. The tooth assembly 10 includes an adapter 12 configured forattachment to the base edges 18 of the implements 2, 7 (FIGS. 1 and 2,respectively), and a ground engaging tip 14 configured for attachment tothe adapter 12. The tooth assembly 10 further includes a retentionmechanism (not shown) securing the ground engaging tip 14 to the adapter12. The retention mechanism may utilize aspects of the adapter 12 andthe ground engaging tip 14, such as retention apertures 16 through thesides of the ground engaging tip 14, but those skilled in the art willunderstand that many alternative retention mechanisms may be implementedin the tooth assemblies 10, and the tooth assemblies 10 are not limitedto any particular retention mechanism(s). As shown in FIG. 4, onceattached to the adapter 12, the ground engaging tip 14 may extendedoutwardly from the base edge 18 of the implement 2, 7 for initialengagement with the work material (not shown).

FIG. 5 illustrates a cross-sectional view of an embodiment of a groundengaging tip 20 in accordance with the present disclosure. The groundengaging tip 20 as shown has a tip body 22 that is generally similar topreviously known ground engaging tips for the tooth assemblies 10. Thetip body 22 is fabricated from an appropriate GET body material having ahardness to provide the ground engaging tip 20 with a sufficient wearlife for the material moving tasks that will be performed and thecharacteristics of the work material that will be moved. Appropriatematerials can include steels of varying harnesses. In applications wheresand, gravel or other abrasive materials severely diminish wear life,and additional material such as hard tungsten carbide particles may bebonded to critical wear areas.

The tip body 22 has an exterior surface 24 extending from an adapterconnection end 26 and converging to a ground engaging end 28. Theadapter connection and 26 includes an adapter cavity surface 30extending inwardly into the tip body 22 and defining an adapter cavity32 for receiving an adapter nose (not shown) of the adapter 12 of theground engaging tooth assembly 10. The ground engaging tip 20 may besecured to the adapter 12 after the adapter nose is inserted into theadapter cavity 32 by attachment hardware inserted through the retentionapertures 16 and engaging the adapter nose.

The exterior surface 24 is generally tapered from the adapter connectionand 26 to the ground engaging and 28. The exterior surface 24 iscontoured to penetrate the work material into which the base edges 18 ofthe implements will dig, and to match the operations performed by theimplements, such as buckets 2, 7. For example, the ground engaging tip20 may be customized for the loader bucket 2 and will scrape a bottomsurface 34 along the ground. Therefore, the tip body 22 may be providedwith more material at the bottom surface 34 where more wear is expected,and with relatively less material at a top surface 36 where less wear isexpected. In a tip body 22 for the excavator bucket 7 or othertop-wearing implementations, more material may be provided at the topsurface 36 and relatively less material at the bottom surface 34. Inother applications, the exterior surface 24 and the adapter cavity 32may be approximately symmetrical about a longitudinal axis of the tipbody 22 so that the tip body 22 is reversible on the adapter 12 so thatone surface 34, 36 can wear during a first period of use, and then thetip body 22 can be flipped over and the opposite surface 34, 36 can wearuntil the tip body 22 must be replaced.

The ground engaging tip 20 in accordance with the present disclosure isconfigured so that the wear life, and importantly the point at which theground engaging tip 20 has reached the end of its useful wear life andshould be replaced, can be detected in a timely manner to allow theground engaging tips 20 to be replaced with minimal interruption to theavailability of the implements 2, 7 and the machines on which they areused. Because the actual use of the work machines varies and thecharacteristics of the work material will vary, the ground engaging tip20 will wear at different rates, and the material of the tip body 22will not wear away in a predictable manner. This makes visual inspectiondifficult, though the point at which the tip body 22 is worn to the endof its useful wear life may be known from the process of designing theground engaging tip 20. In the ground engaging tip 20 having the wearlife sensing system in accordance with the present disclosure, theacoustic properties of the tip body 22 and the material from which it isfabricated may be used to determine when replacement of the groundengaging tip 20 is necessary. Sound can propagate through the materialof the tip body 22 and will be reflected when the sound waves experiencea change in density, such as when the sound waves reach the exteriorsurface 24 of the tip body 22. Unfortunately, due to the contours of theexterior surface 24, the sound waves may reflect that an angle and notdirectly back to the source of the sound waves. Even if the soundwavesource is initially oriented normal to a portion of the exterior surface24, as the tip body 22 wears over time, the contour of the exteriorsurface 24 will change and will not remain normal with respect to thedirection of propagation of the sound waves. Moreover, due to the mixeduses of the implements 2, 7, the tooth assemblies 10 and other GETs onthe various work machines and in the various work environments, there isno set wear pattern for the various designs of the exterior surface 24.Consequently, the exterior surface 24 does not serve as a reliablereference for using sound waves for determining a length of the tip body22 and a corresponding amount of wear that has occurred over time.

The ground engaging tip 20 having the wear life sensing system inaccordance with the present disclosure facilitates the use of soundwaves within the tip body 22 to determine when the tip body 22 is wornto the end of its useful wear life and is ready for replacement. The tipbody 22 is provided with a reference structure within the tip body 22that will provide a consistent reflection of sound waves over time asthe tip body 22 wears. The presence of the reference structure isdetectable based on the reflected sound waves until the tip body 22 andthe reference structure are worn away and the character of the reflectedsound waves changes.

Still referring to FIG. 5, the ground engaging tip 20 may be providedwith a wear sensor assembly 40 of the wear life sensing system that iscapable of outputting distance sensor signals and receiving anddetecting reflected distance sensor signals to determine a distance toan object off of which the distance sensor signals rebound. Toaccommodate the embedding of the wear sensor assembly 40 within the tipbody 22, a wear sensor cavity surface 42 may define a wear sensor cavity44 that receives the wear sensor assembly 40 therein. As illustrated,the wear sensor cavity 44 is a further recess within the adapter cavity32. The wear sensor assembly 40 may be inserted through a wear sensorcavity opening 46, and a wear sensor cavity cap 48 may be installed toretain the wear sensor assembly 40 within the wear sensor cavity 44.

While shown in FIG. 5 is extending inward from the adapter cavity 32,the wear sensor cavity surface 42 and the wear sensor cavity 44 may beformed at any appropriate location within the tip body 22. For example,the wear sensor cavity surface 42 may extend inwardly from the bottomsurface 34 or the top surface 36 in a location where a relatively lightamount of work material engagement and material wear is expected tooccur. Alternatively the wear sensor cavity 44 may be located in anyother appropriate location within the tip body 22 where the wear sensorassembly 40 can propagate sound waves through the tip body 22 for atleast the duration of the wear life of the ground engaging tip 20.

The wear sensor assembly 40 may fit snugly within the wear sensor cavity44 during use of the ground engaging tip 20. Alternatively, ifnecessary, the wear sensor assembly 40 may be suspended within the wearsensor cavity 44 in a conductive gel 50. The conductive gel 50 may be aconductive gelatinous substance that is a conductive medium forpropagating output distance sensor signals 52 and reflected distancesensor signals 54 through the wear sensor cavity 44. One example of sucha conductive gel 50 is the coupling gel used as a conductive medium forthe sound waves generated by an ultrasonic transducer. The conductivegel 50 may have a sufficient density and viscosity to suspend the wearsensor assembly 40 in place within the wear sensor cavity 44 while thework machine operates on the work material. In alternative embodiments,other structures may be used to secure the wear sensor assembly 40 inplace within the wear sensor cavity 44 and allow or facilitatepropagation of the sound waves into the tip body 22.

The ground engaging tip 20 further includes a wear sensing body 60embedded within the tip body 22. The wear sensing body 60 may be locatedwithin the tip body 22 proximate a maximum GET wear point 62. Themaximum GET wear point 62 may be identified by the tip designer as theend of the designed wear life of the ground engaging tip 20 after whichthe ground engaging tip 20 should be replaced. The wear sensing body 60may be embedded into the tip body 22 during the casting or otherfabrication process. For example, the wear sensing body 60 may be formedon a head of a nail (not shown) or other positioning structure withinthe mold for the tip body 22 so that the GET body material will engulfthe wear sensing body 60 when the GET body material is poured into themold. Alternatively, the wear sensing body 60 may be embedded into thetip body 22 after the tip body 22 is formed, such as by inserting thewear sensing body 60 through a pre-molded or post-molding drilledchannel (not shown) into the tip body 22, and with the channel thenbeing backfilled with the GET body material.

To acoustically distinguish the wear sensing body 60 from the tip body22, the wear sensing body 60 is fabricated from a wear sensing bodymaterial having a wear sensing body material density and speed of soundthere through that are different from the density and speed of soundthrough the GET body material. As discussed above, the tip body 22 maybe fabricated from hardened steels, which can have densities rangingfrom 7.75-8.05 g/cm³ (0.28-0.29 ounce/in³), and sounds traveling throughthe tip body 22 at approximately 6,100 m/s (approximately 20,013 ft/s).In contrast, the wear sensing body 60 may be a piece of carbon orgraphite having wear sensing body material densities of approximately2.25 g/cm³ (approximately 0.08 ounce/in³), and having sound travelthrough the wear sensing body at approximately 1,470 m/s (approximately4,823 ft/s). The change in density and speed of sound between the GETbody material and the wear sensing body material will cause the echoedor reflected distance sensor signals 54 when the output distance sensorsignals 52 encounter the wear sensing body 60. The receipt and thedetection of the reflected distance sensor signals 54 at the wear sensorassembly 40 will indicate that the wear sensing body 60 is still presentin the tip body 22 and the tip body 22 is not worn to the maximum GETwear point 62. When the tip body 22 is worn down to the maximum GET wearpoint 62, the wear sensing body 60 will be worn away from the tip body22 and the characteristics of the reflected distance sensor signals 54reflected off the worn down exterior surface 24 will allow the wearsensor assembly 40 to determine that the tip body 22 is at the end ofits useful wear life and should be replaced as discussed furtherhereinafter. Those skilled in the art will understand that the wearsensing body 60 may be fabricated from any other appropriate materialthat will cause a reflection of the output distance sensor signals 52.In further embodiments, an air pocket could be formed within the tipbody 22 proximate the maximum wear point 62, with the change in densityfrom the GET body material and the air causing a similar reflection ofthe output distance sensor signals 52.

Referring to FIG. 6, exemplary configurations of the electrical andcontrol components of the wear sensor assembly 40 and a correspondingexternal GET wear test device 70 of the wear life sensing system areillustrated. The electrical and control components of the wear sensorassembly 40 may be enclosed within a wear sensor assembly housing 72.The illustrated embodiment of the wear sensor assembly 40 may include asensor assembly controller 74 that may be capable of performing theprocessing necessary to determine whether the ground engaging tip 20 isworn to the point of requiring replacement. The sensor assemblycontroller 74 may include a processor 76 for executing a GET wear lifetesting routine performed by the wear sensor assembly 40. The processor76 may be operatively connected to a memory 78 that may have a read onlymemory (ROM) 80 for storing programs, and a random access memory (RAM)82 serving as a working memory area for use in executing a flightcontrol program stored in the ROM 80. Although the processor 76 isshown, it is also possible and contemplated to use other electroniccomponents such as a microcontroller, an application specific integratedcircuit (ASIC) chip, or any other integrated circuit device.

The wear sensor assembly 40 also includes a distance sensor 84operatively connected to the sensor assembly controller 74. The distancesensor 84 is capable of transmitting the output distance sensor signals52 into the tip body 22, and receiving the reflected distance sensorsignals 54 that bounce back from the exterior surface 24 and the wearsensing body 60. The distance sensor 84 can be any appropriatetransceiver capable of transmitting and receiving sound waves throughthe tip body 22 such as, for example, an ultrasonic transceiver. Thedistance sensor 84 may include a transmitter 86 for transmitting theoutput distance sensor signals 52, and a receiver 88 for detecting thereflected distance sensor signals 54. The distance sensor 84 is alsocapable of receiving transmission command signals from the sensorassembly controller 74 that cause the distance sensor 84 to transmit theoutput distance sensor signals 52, and to transmit sensed distancesignals to the sensor assembly controller 74 having values indicative ofthe reflected distance sensor signals 54.

A sensor assembly communications module 90 may be operatively connectedto the sensor assembly controller 74. The sensor assembly communicationsmodule 90 is capable of being controlled by the sensor assemblycontroller 74 to perform wireless communications with the external GETwear test device 70 to receive wear test request messages from theexternal GET wear test device 70 and communicate GET replacementmessages to the external GET wear test device 70. The wear sensorassembly housing 72 may also house a sensor assembly power source 92providing power to the sensor assembly controller 74, the distancesensor 84 and the sensor assembly communications module 90. In oneembodiment, the sensor assembly power source 92 is fully self-contained,and has sufficient storage capability to provide power for the wearsensor assembly 40 for the designed duration of the useful wear life ofthe ground engaging tip 20. In alternative embodiments, the sensorassembly power source 92 may be connected to an external power source(not shown) that may be part of the implement assemblies 1, 6 or themachine in which the ground engaging tips 20 are implemented. A powertransfer connection may be provided via a power cable operativelyconnected between the sensor assembly power source 92 and the externalpower source and extending through the wear sensor cavity cap 48.

The external GET wear test device 70 is configured to communicate withthe wear sensor assembly 40 and to control the wear testing of theground engaging tip 20. The external GET wear test device 70 may be astandalone unit such as a handheld device that may be used by a machineoperator or maintenance worker to initiate the GET wear life testingroutine. Alternatively, the external GET wear test device 70 may beintegrated into the machine that will be using the implement 2, 7 withthe ground engaging tips 20. The components described herein may beadded to the machine, or existing machine components may be modified toprovide the functionality of the external GET wear test device 70, suchas electronic control modules (ECMs), user interface devices andcommunications modules. Still further, the external GET wear test device70 may be implemented at a remote location such as a back office orcontrol center for the owner of the machine. These and additionalalternatives are contemplated by the inventor as having use in GET wearlife testing in accordance with the present disclosure.

Depending on the particular implementation, the external GET wear testdevice 70 may have a test device housing 100 enclosing the electricaland control components. The external GET wear test device 70 asillustrated includes a test device controller 102 capable of controllingthe performance of the GET wear life testing routine, and communicationswith the wear sensor assemblies 40 of the ground engaging tips 20 andthe operators and maintenance workers. Similar to the sensor assemblycontroller 74, the test device controller 102 may include a processor104 and a memory 106 having a ROM 108 and a RAM 110. The external GETwear test device 70 further includes a test device communications module112 that is capable of exchanging communication signals with the sensorassembly communications module 90. A test device power source 114provides power to the other components of the external GET wear testdevice 70. In alternative embodiments, the external GET wear test device70 may be connected to an external power source by appropriate wiring.

The external GET wear test device 70 also may include interface devicesfor communicating with the machine operator or maintenance workerrequesting a wear life test. The external GET wear test device 70 mayhave one or more input devices 116 for inputting commands for the testdevice controller 102. Of particular relevance to the present disclosureare operator input devices 116 providing commands and data related tothe operation of the wear sensor assembly 40 to execute a GET wear lifetesting routine on the ground engaging tip 20. The input devices 116 maybe as simple as a “TEST” button that is pressed to cause the test devicecontroller 102 to execute the GET wear life testing routine, or agraphical user interface such as a touchscreen that may allow a user toenter various types of information and test commands. The output devices118 may be operatively connected to the test device controller 102 toreceive output command signals from the test device controller 102. Theoutput device(s) 118 may be any device capable of providing a sensoryperceptible output to the operator, such as visual display devices,lamps, speakers, and the like. The information communicated to theoperator may include an indication that a ground engaging tip 20 isfully or partially worn to the maximum GET wear point 62, identificationinformation for one or more ground engaging tips 20 that are ready forreplacement, and the like, during and after the performance of the wearlife test routine.

FIG. 7 illustrates an exemplary GET wear life testing routine 120 thatmay be executed by the wear sensor assembly 40 and the external GET weartest device 70 of the wear life sensing system. The GET wear lifetesting routine 120 may be performed at each of the GETs, such as theground engaging tips 20, on the implement 2, 7 simultaneously, or may beperformed at different times, such as more frequently on the GETs thathave been in place on the implement 2, 7 for the longest time and aretherefore likely closest to the end of their wear life, and lessfrequently on new GETs that have been installed more recently in placeof worn out GETs. The selective testing of the GETs may be accomplishedby assigning a unique identifier to each GET that will be stored at thememory 78, or by other methods discussed further hereinafter.

The GET wear life testing routine 120 may begin at a block 122 where thesensor assembly controller 74 may determine whether a wear test requestmessage has been received at the sensor assembly communications module90. The wear test request message may be transmitted from the externalGET wear test device 70 in response to an operator's inputting a GETwear test request command at one of the input devices 116.Alternatively, the test device controller 102 may be configured todetermine when a wear life test should be performed based on factorssuch as the time since the last wear life test, the amount of time theGETs have been installed on the implement 2, 7, the amount of time thework machine has been actively performing material handling functions,and the like. When the test device controller 102 determines that thewear life test should be performed, the test device controller 102 maycause the test device communications module 112 to transmit the wearlife test request message to the GET(s) to be tested. In furtheralternative embodiments, the sensor assembly controller 74 of each GETmay be configured to perform a similar calculation for the appropriatetime to perform a wear life test, and the logic performed at the block122 may be an evaluation by the sensor assembly controller 74 of whetherit is an appropriate time for the wear life test.

If a wear life test request message has not been received at the sensorassembly communications module 90, or the sensor assembly controller 74otherwise determines that it is not time to perform the wear life test,control passes back to the block 122 to continue evaluating whether thewear life test should be performed. If a wear life test request messageis received or it is time for a GET wear life test at the block 122.Control passes to a block 124 where the sensor assembly controller 74causes the distance sensor 84 to output the output distance sensorsignals 52. In the illustrated embodiment, the transmitter 86 of theultrasonic transceiver 84 will output ultrasonic waves through theconductive gel 50 and into the tip body 22 in the general direction ofthe ground engaging and 28. As the ultrasonic waves travel through thetip body 22, they are fully or partially reflected when they reach thewear sensing body 60 or the exterior surface 24 and experience changesin the material density and the speed of sound.

The reflection of the output distance sensor signals 52 off the wearsensing body 60 creates reflected distance sensor signals 54 back in thedirection of the wear sensor assembly 40. Depending on the shape of theexterior surface 24 at a given time, some reflected distance sensorsignals 54 from the exterior surface 24 may also be directed back to thewear sensor assembly 40. To determine the presence of and distance tothe wear sensing body 60, control of the GET wear life testing routine120 passes to a block 126 where the reflected distance sensor signals 54are received at the distance sensor 84. Upon receipt, the distancesensor 84 transmits corresponding messages to the sensor assemblycontroller 74.

When the reflected distance sensor signals 54 are received at thedistance sensor 84 and the messages are transmitted to the sensorassembly controller 74, control passes to a block 128 where the sensorassembly controller 74 determines a status of the wear sensing body 60.The sensor assembly controller 74 may be configured to use techniquesknown in the art for determining the distance to an object based onsound waves. Because the wear sensing body 60 is embedded in andstationary within the GET body, such as the tip body 22, the reflecteddistance sensor signals 54 from the wear sensing body 60 will beconstant as long as the wear sensing body 60 is still in the GET bodyregardless of the shape of the exterior surface 24. Consequently, thereflected distance sensor signals 54 for the wear sensing body 60 willbe consistent when the GET is new as shown for the ground engaging tip20 in FIG. 5, or is partially worn down as shown in FIG. 8, but not worndown to the maximum GET wear point 62. As long as the reflected distancesensor signals 54 remain consistent, the sensor assembly controller 74will determine that the wear sensing body 60 is present and the GET isnot at the end of its useful wear life.

After the sensor assembly controller 74 determines the status of thewear sensing body 60 at the block 128, control passes to a block 130where the sensor assembly controller 74 uses the status of the wearsensing body 60 to determine whether the GET should be replaced. If thesensor assembly controller 74 determines that the wear sensing body 60is still present at the block 130, the GET does not need to be replacedand control passes back to the block 122 to wait for the next tip wearlife test request. If the sensor assembly controller 74 determines thatthe wear sensing body 60 is gone, then the GET is at the end of the itsuseful wear life. FIG. 9 illustrates an example of the ground engagingtip 20 worn down to the point that the wear sensing body 60 is worn awayfrom the tip body 22. As illustrated, the tip body 22 has also worn pastthe maximum GET wear point 62 since the previous wear life test. Withoutthe wear sensing body 60, the output distance sensor signals 52 reflectsoff the exterior surface 24. The character of the reflected distancesensor signals 54 changes to indicate the decreased distance to theexterior surface 24. In response to this change in the character anddistance, the sensor assembly controller 74 determines that the wearsensing body 60 is gone from the tip body 22 and, correspondingly, thatthe ground engaging tip 20 should be replaced.

When the sensor assembly controller 74 determines that the wear sensingbody 60 is gone at the blocks 128, 130, control passes to a block 132where the sensor assembly controller 74 causes the sensor assemblycommunications module 90 to transmit a GET replacement message to theexternal GET wear test device 70. The GET replacement message mayinclude an indication of the specific GET that transmitted the GETreplacement message. For example, each GET may be assigned a uniqueidentifier that is stored in the memory 78 of the wear sensor assembly40. The GET placement message may then be formatted with the uniqueidentifier so that the operator of the external GET wear test device 70knows which GET requires replacement. When the GET replacement messageis received at the test device communications module 112, the testdevice controller 102 will cause the output device 118 to produce asensory perceptible output to the operator, such as a flashing light, anotification sound, or a message on a visual display, alerting theoperator that the GET should be replaced. After the GET replacementmessage is transmitted at the block 132, the GET wear life testingroutine 120 may terminate.

The GET may be modified as necessary to ensure that the wear status ofthe GET is known accurately and the GET can be replaced in a timelymanner when it reaches the end of its useful wear life. Referring toFIG. 10, the GET in the form of the ground engaging tip 20 is configuredto detect wear at multiple locations. This may be desirable if theground engaging tip 20 or other GETs may have differing wear patternsdepending on the use of the implement 2, 7. For example, the groundengaging tip 20 may wear from the ground engaging end 28 toward theadapter connection and 26 as shown in the sequence of FIGS. 5, 8, 9 ifthe implement 2, 7 digs into the work material, or the ground engagingtip 20 may wear up from the bottom surface 34 if the implement 2, 7 doesa significant amount of scraping along the ground. To account for thelatter wear pattern, the ground engaging tip 20 may include a secondwear sensor assembly 140 and a second wear sensing body 142 within thetip body 22.

The second wear sensor assembly 140 may have a similar configuration asthe first wear sensor assembly 40, with a second sensor assemblycontroller 74, a second processor 76, a second memory 78, a seconddistance sensor 84, and a second sensor assembly communications module90. The wear sensor cavity 44 may be large enough to house both wearsensor assembly 40, 140, or a second wear sensor cavity surface 144 maydefine a second wear sensor cavity 146 with a second wear sensor cavityopening 148 closed by a second wear sensor cavity cap 150 to retain thesecond wear sensor assembly 140 and conductive gel 50 within the secondwear sensor cavity 146. The second wear sensing body 142 is embedded inthe GET body proximate a second maximum GET wear point 152 for wear upfrom the bottom surface 34. The second wear sensor assembly 140 may bedirected at the second wear sensing body 142 so that second outputdistance sensor signals 154 reflected off the second wear sensing body142 to generate second reflected distance sensor signals 156. The secondwear sensor assembly 140 may execute the GET wear life testing routine120 in the manner described above so that the GET replacement message istransmitted when either of the wear sensing bodies 60, 142 is worn awayfrom the GET body. The wear sensor assemblies 40, 140 and the wearsensing bodies 60, 142 may be positioned at alternative locations thatmay indicate when it is desirable to replace the GET, and additionalwear sensor assemblies 40, 140 and wear sensing bodies 60, 142 may beused within the GETs.

FIG. 11 illustrates a further alternative embodiment where the wearcondition of the GET is determined and communicated to the operator atintermediate points as the GET body wears toward the maximum GET wearpoint 62. As shown, a second wear sensing body 160 is embedded in thetip body 22 at a partial GET wear point 162. The second wear sensingbody 160 will create second reflected distance sensor signals 164 thatare received at the distance sensor 84. With multiple wear sensingbodies 60, 160, the sensor assembly controller 74 may execute a modifiedGET wear life testing routine 170 shown in FIG. 12. The modified GETwear life testing routine 170 may start with blocks 122, 124, 126 asdescribed above. Control may then pass to a block 172 where the sensorassembly controller 74 may determine the statuses of all the wearsensing bodies 60, 160 from the reflected distance sensor signals 54,164. The reflected distance sensor signals 54, 164 will be consistentwhile the wear sensing bodies 60, 160 are still embedded in the GETbody, and will change as the wear sensing bodies 60, 160 are worn awayin turn. If no wear sensing bodies 60, 160 are gone at the block 130,control passes back to the block 122 until the next wear test request.

If a wear sensing body 60, 160 is determined to be gone from the GETbody at the block 130, control passes to a block 174 to determinewhether the last wear sensing body 60 is gone. If the wear sensing body60 is not gone, the GET is not yet at the end of its useful wear life,but the GET body has worn to the partial GET wear point 162. In thissituation, control passes to a block 178 to transmit a GET partial wearmessage to the external GET wear test device 70. The external GET weartest device 70 may respond by outputting an appropriate message to theoperator at the output device 118. The message may alert the operator ormaintenance workers so that replacement of the GET may be scheduledbefore the GET body wears to the maximum GET wear point 62. If thesensor assembly controller 74 determines that the last wear sensing body60 is gone at the block 174, control passes to the block 132 to transmitthe GET replacement message as discussed above.

INDUSTRIAL APPLICABILITY

The wear life sensing system in accordance with the present disclosuremay provide for accurate and timely determination that the GETs havereached the ends of their useful wear lives and should be replaced sothat the work machines can operate most efficiently. The wear lifesensing system and the GET wear life testing routines 120, 170 utilizeknown methods of non-destructive inspection using sound waves to detectand determine distances to objects or irregularities within solidbodies. The wear sensing bodies 60, 142, 160 embedded within the GETsprovide fixed reference points for determining at a minimum when theGETs should be replaced, and can provide intermediate wear indicationswhen the GETs are partially worn. As long as the wear sensing bodies 60,142, 160 are present in the GETs, the GETs have remaining useful wearlife and provide acceptable ground engaging performance for theimplements 2, 7. When the wear sensing bodies 60, 142, 160 are no longerpresent in the GETs, the operator or maintenance works will be notifiedwith reliable information that the GETs are at the ends of their usefulwear lives.

While the preceding text sets forth a detailed description of numerousdifferent embodiments, it should be understood that the legal scope ofprotection is defined by the words of the claims set forth at the end ofthis patent. The detailed description is to be construed as exemplaryonly and does not describe every possible embodiment since describingevery possible embodiment would be impractical, if not impossible.Numerous alternative embodiments could be implemented, using eithercurrent technology or technology developed after the filing date of thispatent, which would still fall within the scope of the claims definingthe scope of protection.

It should also be understood that, unless a term was expressly definedherein, there is no intent to limit the meaning of that term, eitherexpressly or by implication, beyond its plain or ordinary meaning, andsuch term should not be interpreted to be limited in scope based on anystatement made in any section of this patent (other than the language ofthe claims). To the extent that any term recited in the claims at theend of this patent is referred to herein in a manner consistent with asingle meaning, that is done for sake of clarity only so as to notconfuse the reader, and it is not intended that such claim term belimited, by implication or otherwise, to that single meaning.

What is claimed is:
 1. A ground engaging tip of a ground engaging toothassembly for an implement of a work machine that engages a work materialwith a base edge of the implement to dig into the work material, theground engaging tip comprising: a tip body having an exterior surfaceshaped to penetrate the work material into which the base edge of theimplements digs, an adapter cavity surface defining an adapter cavityfor receiving an adapter nose of an adapter of the ground engaging toothassembly to mount the ground engaging tip on the adapter, and a firstwear sensor cavity surface defining a first wear sensor cavity withinthe ground engaging tip, wherein the tip body is fabricated from aground engaging tool (GET) body material having a GET body materialdensity; a first wear sensing body embedded in the tip body at a firstlocation indicative of a first maximum GET wear point of the groundengaging tip, wherein the first wear sensing body is fabricated from awear sensing body material having a wear sensing body material densitythat is not equal to the GET body material density; and a first wearsensor assembly disposed within the first wear sensor cavity, the firstwear sensor assembly comprising: a first distance sensor fortransmitting output distance sensor signals and for receiving reflecteddistance sensor signals that are reflected from an object or a surfaceof the tip body, and a first sensor assembly controller operativelyconnected to the first distance sensor, the first sensor assemblycontroller being configured to: cause the first distance sensor totransmit the output distance sensor signals, detect receipt of thereflected distance sensor signals at the first distance sensor,determine whether the first wear sensing body is still embedded in thetip body proximate the first maximum GET wear point based on a value ofthe reflected distance sensor signals, and cause a GET replacementmessage to be transmitted from the first wear sensor assembly inresponse to determining that the first wear sensing body is no longerembedded in the tip body.
 2. The ground engaging tip of claim 1,comprising: a first conductive gelatinous substance disposed within thefirst wear sensor cavity and suspending the first wear sensor assemblywithin the first wear sensor cavity, wherein the first conductivegelatinous substance is a conductive medium for propagating the outputdistance sensor signals and the reflected distance sensor signalsthrough the first wear sensor cavity between the first distance sensorand the tip body; and a first wear sensing cavity cap covering a firstwear sensor cavity opening to retain the first wear sensor assembly andthe first conductive gelatinous substance within the first wear sensingcavity.
 3. The ground engaging tip of claim 1, wherein the first wearsensor assembly comprises a first sensor assembly power source operablycoupled to the first sensor assembly controller and the first distancesensor.
 4. The ground engaging tip of claim 1, wherein the first wearsensor assembly comprises a first sensor assembly communications moduleoperably coupled to the first sensor assembly controller, wherein thefirst sensor assembly controller is configured to cause the first sensorassembly communications module to transmit the GET replacement messagein response to determining that the first wear sensing body is no longerembedded in the tip body.
 5. The ground engaging tip of claim 4, whereinthe first sensor assembly controller is configured to detect receipt atthe first sensor assembly communications module of a wear test requestmessage from an external GET wear test device, and to cause the firstdistance sensor to transmit the output distance sensor signals inresponse to detecting receipt of the wear test request message.
 6. Theground engaging tip of claim 1, comprising a second wear sensing bodyfabricated from the wear sensing body material and embedded in the tipbody at a second location indicative of a partial GET wear point of theground engaging tip, wherein the first sensor assembly controller isconfigured to: determine whether the second wear sensing body is stillembedded in the tip body proximate the partial GET wear point based onthe value of the reflected distance sensor signals, and cause a GETpartial wear message to be transmitted from the first wear sensorassembly in response to determining that the second wear sensing body isno longer embedded in the tip body and the first wear sensing body isstill embedded in the tip body.
 7. The ground engaging tip of claim 1,wherein the tip body has a second wear sensor cavity surface defining asecond wear sensor cavity within the tip body, the ground engaging tipcomprising: a second wear sensing body embedded in the tip body at asecond location indicative of a second maximum GET wear point of theground engaging tip, wherein the second wear sensing body is fabricatedfrom the wear sensing body material; and a second wear sensor assemblydisposed within the second wear sensor cavity, the second wear sensorassembly comprising: a second distance sensor for transmitting outputdistance sensor signals and for receiving reflected distance sensorsignals that are reflected from an object or a surface of the tip body,and a second sensor assembly controller operatively connected to thesecond distance sensor, the second sensor assembly controller beingconfigured to: cause the second distance sensor to transmit the outputdistance sensor signals, detect receipt of the reflected distance sensorsignals at the second distance sensor, determine whether the second wearsensing body is still embedded in the tip body proximate the secondmaximum GET wear point based on the value of the reflected distancesensor signals, and cause the GET replacement message to be transmittedfrom the second wear sensor assembly in response to determining that thesecond wear sensing body is no longer embedded in the tip body.
 8. Awear life sensing system, comprising: the ground engaging tip of claim1; and an external GET wear test device, comprising: an input device,and a test device controller operatively connected to the input device,wherein the test device controller is configured to: detect input of aGET wear test request command at the input device, and transmit a weartest request message to the first wear sensor assembly in response todetecting the GET wear test request command at the input device, whereinthe first sensor assembly controller is configured to: receive the weartest request message transmitted by the external GET wear test device,and cause the first distance sensor to transmit the output distancesensor signals in response to receiving the wear test request message.9. The wear life sensing system of claim 8, wherein the external GETwear test device comprises an output device operatively connected to thetest device controller, wherein the test device controller is configuredto: receive the GET replacement message transmitted by the first wearsensor assembly, and cause the output device to output a sensoryperceptible output indicating that the ground engaging tip is worn tothe first maximum GET wear point in response to receiving the GETreplacement message.
 10. A method for sensing an amount of wear in aground engaging tool for an implement of a work machine that engages awork material to dig into the work material, the method comprising:transmitting output distance sensor signals through a ground engagingtool (GET) body of the ground engaging tool from a first distance sensorof a first wear sensor assembly disposed within a first wear sensorcavity within the GET body, wherein the GET body is fabricated from aGET body material having a GET body material density, and wherein afirst wear sensing body is embedded in the GET body at a first locationindicative of a first maximum GET wear point of the ground engagingtool, and the first wear sensing body is fabricated from a wear sensingbody material having a wear sensing body material density that is notequal to the GET body material density; receiving reflected distancesensor signals at the first distance sensor that are reflected from oneof an object or a surface of the GET body; determining at the first wearsensor assembly whether the first wear sensing body is still embedded inthe GET body proximate the first maximum GET wear point based on a valueof the reflected distance sensor signals; and transmitting a GETreplacement message from the first wear sensor assembly in response todetermining that the first wear sensing body is no longer embedded inthe GET body.
 11. The method of claim 10, comprising: receiving a weartest request message at the first wear sensor assembly; and transmittingthe output distance sensor signals in response to receiving the weartest request message.
 12. The method of claim 11, comprisingtransmitting the wear test request message from an external GET weartest device.
 13. The method of claim 12, comprising: receiving the GETreplacement message at the external GET wear test device; and outputtinga sensory perceptible output at the external GET wear test deviceindicating that the ground engaging tool is worn to the first maximumGET wear point in response to receiving the GET replacement message atthe external GET wear test device.
 14. The method of claim 11,comprising waiting for additional wear test request messages to bereceived at the first wear sensor assembly in response to determiningthat the first wear sensing body is still embedded in the GET body. 15.The method of claim 11, comprising: transmitting output distance sensorsignals through the GET body from a second distance sensor of a secondwear sensor assembly disposed within a second wear sensor cavity withinthe GET body, wherein a second wear sensing body is embedded in the GETbody at a second location indicative of a second maximum GET wear pointof the ground engaging tool, and wherein the second wear sensing body isfabricated from the wear sensing body material; receiving reflecteddistance sensor signals at the second distance sensor that are reflectedfrom one of an object or a surface of the GET body; determining at thesecond wear sensor assembly whether the second wear sensing body isstill embedded in the GET body proximate the second maximum GET wearpoint based on the value of the reflected distance sensor signals; andtransmitting a GET replacement message from the second wear sensorassembly in response to determining that the second wear sensing body isno longer embedded in the GET body.
 16. The method of claim 10, whereina second wear sensing body fabricated from the wear sensing bodymaterial is embedded in the GET body at a second location indicative ofa partial GET wear point of the ground engaging tool, the methodcomprising: determining whether the second wear sensing body is stillembedded in the GET body proximate the partial GET wear point based onthe value of the reflected distance sensor signals; and transmitting aGET partial wear message from the first wear sensor assembly in responseto determining that the second wear sensing body is no longer embeddedin the GET body and the first wear sensing body is still embedded in theGET body.
 17. A ground engaging tool for an implement of a work machinethat engages a work material to dig into the work material, the groundengaging tool comprising: a ground engaging tool (GET) body having anexterior surface shaped to penetrate the work material into which theimplements digs, and a first wear sensor cavity surface defining a firstwear sensor cavity within the GET body, wherein the GET body isfabricated from a GET body material having a GET body material density;a first wear sensing body embedded in the GET body at a first locationindicative of a first maximum GET wear point of the ground engagingtool, wherein the first wear sensing body is fabricated from a wearsensing body material having a wear sensing body material density thatis not equal to the GET body material density; and a first wear sensorassembly disposed within the first wear sensor cavity, the first wearsensor assembly comprising: a first distance sensor for transmittingoutput distance sensor signals and for receiving reflected distancesensor signals that are reflected from an object or a surface of the GETbody, and a first sensor assembly controller operatively connected tothe first distance sensor, wherein the first sensor assembly controlleris configured to: cause the first distance sensor to transmit the outputdistance sensor signals, detect receipt of the reflected distance sensorsignals at the first distance sensor, determine whether the first wearsensing body is still embedded in the GET body proximate the firstmaximum GET wear point based on a value of the reflected distance sensorsignals, and cause a GET replacement message to be transmitted from thefirst wear sensor assembly in response to determining that the firstwear sensing body is no longer embedded in the GET body.
 18. The groundengaging tool of claim 17, comprising a second wear sensing bodyfabricated from the wear sensing body material and embedded in the GETbody at a second location indicative of a partial GET wear point of theground engaging tool, wherein the first sensor assembly controller isconfigured to: determine whether the second wear sensing body is stillembedded in the GET body proximate the partial GET wear point based onthe value of the reflected distance sensor signals, and cause a GETpartial wear message to be transmitted from the first wear sensorassembly in response to determining that the second wear sensing body isno longer embedded in the GET body and the first wear sensing body isstill embedded in the GET body.
 19. The ground engaging tool of claim17, wherein the GET body has a second wear sensor cavity surfacedefining a second wear sensor cavity within the GET body, the groundengaging tool comprising: a second wear sensing body embedded in the GETbody at a second location indicative of a second maximum GET wear pointof the ground engaging tool, wherein the second wear sensing body isfabricated from the wear sensing body material; and a second wear sensorassembly disposed within the second wear sensor cavity, the second wearsensor assembly comprising: a second distance sensor for transmittingoutput distance sensor signals and for receiving reflected distancesensor signals that are reflected from an object or a surface of the GETbody, and a second sensor assembly controller operatively connected tothe second distance sensor, wherein the second sensor assemblycontroller is configured to: cause the second distance sensor totransmit the output distance sensor signals, detect receipt of thereflected distance sensor signals at the second distance sensor,determine whether the second wear sensing body is still embedded in theGET body proximate the second maximum GET wear point based on the valueof the reflected distance sensor signals, and cause the GET replacementmessage to be transmitted from the second wear sensor assembly inresponse to determining that the second wear sensing body is no longerembedded in the GET body.
 20. A wear life sensing system, comprising:the ground engaging tool of claim 17; and the external GET wear testdevice, comprising: an input device, an output device, a wear testdevice communications module, and a test device controller operativelyconnected to the input device, the output device and the wear testdevice communications module, wherein the test device controller isconfigured to: detect input of a GET wear test request command at theinput device, cause the wear test device communications module totransmit a wear test request message to the first wear sensor assemblyin response to detecting the GET wear test request command at the inputdevice, detect receipt at the wear test device communications module ofthe GET replacement message by the first wear sensor assembly, and causethe output device to output a sensory perceptible output indicating thatthe ground engaging tool is worn to the first maximum GET wear point inresponse to receiving the GET replacement message.